The present invention relates to a brake apparatus for an automotive vehicle, and more specifically to a brake apparatus for industrial vehicles, in which brake operation is effected on the basis of engagement an annular V-shaped groove of a wheel hub and a V-shaped brake member of a steering knuckle.
As an example of conventional brake apparatus for automotive vehicles, Japanese Utility Model Kokoku Publication No. 50-30533 (examined) discloses a disk brake apparatus. In this apparatus, as shown in FIG. 1, a spindle 21 is fixed to a steering knuckle (not shown) is disposed passing through a wheel hub 22, and the wheel hub 22 is rotatably supported by a pair of tapered roller bearings 23 and 23 disposed between the spindle 21 and the wheel hub 22. A disk rotor 25 and a disk wheel (not shown) are mounted on the wheel hub 22 by bolts 24, and further a caliper 26 is attached to the steering knuckle (not shown).
In this conventional disk brake apparatus, although braking force can be obtained by sandwiching the disk rotor 25 with a pair of pads 27 and 27 retained on the caliper 26, since a pair of tapered roller bearings 23 are used for supporting the spindle 21 as described above, no special consideration is taken about an axial force applied to the spindle 21. This is because in the case with the disk brake, no heavy load is produced in the axial direction of the bearings in brake operation. Further, in case where this brake apparatus is mounted on the rear wheel of an FR vehicle, it has been unnecessary to take a special consideration to the axial load produced during vehicle running.
Recently, there have been noted of an increasing number of the FF vehicles. However, in the FF vehicles, a great axial force is exerted to the brake apparatus mounted on the front wheels during steering of the vehicle. Therefore, when a great axial force is exerted to the conventional brake apparatus, as already explained, there exists a problem in that the bearings 23 may become loose or dismounted and thus it is impossible to mount the conventional brake apparatus on the front wheels of an FF vehicle to which a great axial force is exerted.
In addition, in the front wheels of an FF vehicle, since the brake apparatus should be mounted together with a front wheel driving mechanism and a steering mechanism, it is also necessary to minimize and simplify the brake apparatus structure. In other words, there has existed a strong demand of developing a small-sized and simplified brake apparatus for an automotive vehicle, which can withstand a heavy axial load in both braking and steering operations.
Further, in the case of the conventional brake apparatus disclosed in Japanese Patent Kokai Publication No. 61-55415, a V-shaped groove (referred to as "V groove") formed into an equilateral triangular shape in cross section is provided on one side surface of a rotary disk, and two annular sliding surfaces are provided on the inner and outer circumferential sides so that friction members can slidably fit to the sliding surfaces. In a brake apparatus having two or more friction surfaces, in general, when an axial load is applied thereto, a biased wear (unbalanced wear) is easily produced on the brake friction surfaces. Therefore, it is also desired to prevent this biased wear.